More Analysis of the Fake Birdman Video

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More Analysis of the Fake Birdman Video

Ok. Why analyze something that is fake? One, it is fun and challenging to show convincingly it is fake. Two, because I wrote this and was 99% finished, when this dumb story came out: 'Bird Man' Hoaxster Comes Clean on Dutch Television. Great. The fun is over. Everyone go home.

But wait. I already did all this analysis. Why waste it? I think this was a great fake for the following reasons:

It seemed to be on the boundary of the believable/unbelievable line. If it had been something super crazy, no one would even question it.

The video passed my first order test for fakedness - the fake camera shake.

The motions of the man seemed extreme, but people can do extreme things - so it wasn't way past the line of physically possible.

Finally, I think the biggest part is his devotion to this hoax. He has been slowly building up his story over time. And for that, I applaud the Bird Man and his hoax. Good job on the patience.

Now, I will leave the rest of this post. I still like it as it is.

Pre-News Post
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I love this story of the man made birdwings. Why? Because someone posting something extraordinary is like a stick poking in a bee hive called the internet. Look at all the activity it created. People say it is real, people say it is fake. Sure, some people get a little emotionally involved, but it is still interesting. Ok, if you are new to the story, here is a nice summary of the Human Birdwings story.

So, what do we do now? I think I was too quick when I looked at the camera motion in the video. Recall that some fake videos add fake camera shake to make the video seem more reasonable. Let me look at the motion for the helmet camera in the Birdman video.

Here are two plots. The first is the position of an object in the background from the view of the helmet camera (which looks like a GoPro camera) while the guy is running to take off.

The axis units are just in terms of pixels or something. I did normalize all the videos so that they are have the same width (though maybe not the same angular size). Here is a the same thing for the part where Birdman is flying:

You wouldn't expect these to be exactly the same, would you? In one case the dude is running and flapping his arms. In the other he is just flapping. So, how would I look for fake camera shake? How about a comparison video? Here I found a short video of a guy with a GoPro camera on a short hang glider trip. Check it out.

I am pretty sure this video is real. Let me just assume that it's real. What if I do the same thing and look at the background motion for this helmet camera? Here it is:

This looks much smoother and more like a random walk or something than the Birdman video. But who do I quantify the difference? I have no idea. Let me start with an example. Here are 4 points for the motion of the background. For each new point in the video, I can make a vector that describes the "jump" in the background.

How about I calculate the pixel jump in each frame and then plot a histogram of the jump size? Yes. Let's do it. Here are the plots for the Birdman while he is flying and the hang glider.

Not a giant difference, but there is a difference. The width of the hang glider distribution looks smaller than the Birdman motion (the histograms are not scaled the same on the horizontal axis). Here are some stats on the distributions:

Birdman: average jump = 13.44, standard deviation = 7.23

Hang Glider: average jump = 2.73, standard deviation = 1.56

Oh, these distributions have the same numbers in plots above. So, with the same number of data points, the hang glider has a much smaller average jump between frame as well as a much smaller standard deviation. One cause might be the frame rate. The Birdman video is a 25 frame per second video where the hang glider is 30 fps. So, if I account for this difference the Birdman would still have an average jump of 11.3 (the units I guess would be pixels - but remember, I normalized the video size).

But when I look at the "trajectory" of these two plots, the distance for each jump doesn't stand out to me. It is the angle between successive jumps. The Birdman video looks MUCH sharper in the jumps.

Here is a histogram of the angles between successive jumps in the video for the Birdman:

This has a average angle "jump" of 172.99° with a standard deviation of 104.6°. What about the hang glider video?

This looks fairly similar to the Birdman angles. I think the Birdman looks so much more dramatic with the angles because the jump size is so much larger. The hang glider data has an average of 185.87° with a standard deviation of 102.5°. No significant difference.

What about a plot of the jump size as a function of frame number? Here you go.

The blue is the Birdman video. You can see how much larger the jump size is.

Conclusion
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Alas, still no smoking gun evidence. I think we can all agree that the Birdman video is much jumpier than the hang glider video I used, but maybe that could be attributed to the activity of the Birdman. I hate to pick on this video too much, but the popular opinion is that it is fake (and now we KNOW it is fake).

Why do I keep looking at this video? I think it is a great example of some of the elements of science. We collect evidence, and we try to build an idea. It is really impossible to show that any idea is THE TRUTH. However, we can show that something is NOT TRUE. For example, suppose I want to say that when I let go of an object it always falls. How would I prove this to be true? Well, I would have to take every single object in the universe and drop it to see what happens. However, if I just find one object that does not fall, then I can show this idea is not true.

Maybe Indiana Jones said this best in Indiana Jones and the Last Crusade:

Yes, in this case someone knows the truth (well, now EVERYONE knows the truth) - but I still love this quote for both science and archeology.

Oh, one more note. I think I need to work on my fake camera shake detection methods. Although, wouldn't it be cool if the Birdman made his video explicitly to pass my shake test? That would be cool. Let the fake video arm wars begin.